Electrically insulating sealing structure and its method of use in a

Abstract

In accordance with the present invention, an insulating sealing structure useful in physical vapor deposition apparatus is provided. The insulating sealing structure is capable of functioning under high vacuum and high temperature conditions. The apparatus is a three dimensional structure having a specifically defined range of electrical, chemical, mechanical and thermal properties enabling the structure to function adequately as an insulator which does not break down at voltages ranging between about 1,500 V and about 3,000 V, which provides a seal against a vacuum of at least about 10.sup.-6 Torr, and which can function at a continuous operating temperature of about 300.degree. F. (148.9.degree. C.) or greater. The insulating sealing structure may be fabricated solely from particular polymeric materials or may comprise a center reinforcing member having at least one layer applied to its exterior surface, where the at least one surface layer provides at least a portion of the insulating properties and provides the surface finish necessary to make an adequate seal with a mating surface. A first preferred embodiment comprises an aluminum center reinforcing member having at least one layer of a polymeric insulator applied to provide an insulating, sealing surface. A second preferred embodiment comprises an anodized aluminum center reinforcing member having an inorganic insulator such as silicon oxide, silicon nitride, or aluminum nitride applied to provide the insulating, sealing surface. A third preferred embodiment comprises a graphite, silica or glass fiber-reinforced member having at least one layer of a polymeric insulator applied thereover, to provide an insulating sealing surface. A fourth preferred embodiment comprises a silicon nitride or graphic fiber-reinforced member having an inorganic, non-metallic insulating sealing surface thereover.